REDMOND, Wash. — People are spending hours each week commuting to work, often via bus, so why not turn that into workout time? Just retrofit buses with exercise equipment like stationary bikes and rowing machines, with seatbelts, and give commuters a new way to multitask.

That concept, dubbed “Work to Work,” was one of the startup business ideas floated this weekend by budding teen entrepreneurs during the Innovate ’17 startup bootcamp and pitch contest, and it seemed like a great concept, in theory … until the panel of judges started asking questions. What about safety, insurance, and the downsides of arriving at work all sweaty? And will companies really deploy multiple shuttle buses for regular and exercising commuters?

No, coming up with a startup idea isn’t easy, but as dozens of teens learned over the span of two weekends, it can be exciting, rewarding and a lot of fun.